Networkable Zone Control Modules and Method and Conveyor System Incorporating the Same

ABSTRACT

A package control conveyor system comprises a plurality of independently-controllable package conveying units each of which comprises a zone control module operably connected to a package sensing device and a package conveying unit for selectively activating and deactivating the package conveying unit, wherein the zone control modules are communicably interconnected upstream and downstream so that each zone control module can selectively activate and deactivate its associated package conveying unit in response to information provided by one or more upstream and/or downstream zone control modules.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/383,890, filed Mar. 7, 2003, which claims the benefit of U.S.provisional application Ser. No. 60/319,140, filed Mar. 8, 2002, whichare incorporated herein in their entirety.

FIELD OF THE INVENTION

This invention relates to a conveyor system having zone control moduleswhich can detect product on an attached conveyor. More specifically, theinvention relates to a zone control module which can be programmed withspecific features and operational criteria by various hard wired orwireless devices. Additionally, the invention relates to a conveyorcontrol system that can have several interconnected zone control moduleswhich can pass operational information to one another using a simplifiedcommunications protocol, and to an interface which translates thesimplified protocol to a standard communications network protocol thatcan communicate with a standard PC-based or networked computerenvironment.

DESCRIPTION OF THE RELATED ART

Conveyor control systems typically include one or more “zone” controlmodules which let a controller for the conveyor system detect the status(i.e. location) of objects being conveyed on the system. An example ofsuch a system is disclosed in U.S. Pat. No. 6,302,266, issued Oct. 16,2001, which discloses a conveyor system comprising a series of rollersrotatably mounted to a frame. The rollers are organized into roller“zones” in which the rollers in a zone operate in concert. Acontinuous-loop drive belt passes beneath the rollers, and isselectively brought into contact with a selected roller zone by apneumatic actuator which, when actuated, extends to abut the belt with aselected number of rollers, and, when retracted, removes the abutment ofthe belt with the rollers. A plurality of interconnected zone controlmodules and photo-electric sensing devices (often referred to as“photo-eyes”) are mounted in a suitable fashion at regular intervals tothe frame, with each zone control module and photo-eye operablyassociated with a specific zone. Each zone control module incorporates asolenoid-driven pneumatic valve for delivering pressurized air to thepneumatic actuator serving that module. A signal from the photo-eye,indicating the presence or absence of a package on the associated zone,will activate the zone control module and the pneumatic actuator for aspecific zone.

One problem with the prior art network or PC-based conveyor systems isthat they are typically server-based systems, where every zone controlmodule must be separately connected to the server. Furthermore, eachzone control module must have a unique ID, which must be reprogrammedinto the system contol program when the zone control module is replaced,or new modules added. Wiring must typically be run to each zone controlmodule, and then bussed to a controller which must decipher which zonethe information came from.

This problem has been addressed by providing conveyor control moduleswith microprocessors which can deliver additional information viastandard networking/communication protocols (i.e. RS-232). However,there remain problems with the prior art conveyor systems. These priorart devices require accurate positioning information to determine thezone control module's location in a series of modules. Often, standardnetworking protocols require a unique zone control module ID for eachmodule, making replacement and repair to conveyor control systemsdifficult.

SUMMARY OF THE INVENTION

In an embodiment of the invention, a method for controlling a conveyorsystem separated into a plurality of contiguousindependently-controllable zones comprises the steps of providing aplurality of actuators, each actuator operably interconnected to aparticular one of the plurality of independently-controllable zones,wherein each actuator operates the movement of at least one object inthe particular zone, providing a plurality of controllers having asignal processor/generator therein, operably interconnecting eachcontroller with a particular one of the plurality of actuators forselective actuation of the particular actuator and operablyinterconnecting the controller with at least one of an adjacent upstreamcontroller and an adjacent downstream controller, and having eachcontroller perform at least one of the following steps: detecting thepresence of at least one object local to the controller and performingat least one event logic element responsive to the detecting step,receiving a signal from at least one of the adjacent upstream controllerand the adjacent downstream controller and performing at least one eventlogic element responsive to the signal, or detecting a change in anoperating condition stored by the controller and performing at least oneevent logic element responsive to the changed operating condition.

The method can further comprise the steps of initiating the operation ofa delay timer in response to the presence of an object in a zone localto the controller or terminating the operation of the delay timer inresponse to the absence of an object in a zone local to the controllerfor a predetermined period of time. The absence of the object can becommunicated to at least one adjacent upstream controller. The resultsof the detecting step can be stored in the controller to serve as areference for further evaluation of the presence of an object in thezone, and communicated to at least one adjacent upstream controller.

The method can further comprise the step of responding to a signalrepresentative of an auto-slug condition received from at least oneadjacent downstream controller. The existence of a jammed objectcondition exists in a zone local to the controller can be determined. Areceived signal relating to the jammed object condition can be stored toserve as a reference for evaluation of a subsequent received signalrepresentative of a jammed object condition. The operation of a delaytimer can be initiated in response to a detected jammed objectcondition. The operation of the delay timer can be terminated when thejammed object condition fails to be detected for an acceptable period oftime. The signal can be communicated to at least one adjacent upstreamcontroller representative of the jammed object condition.

The method can further comprise the step of responding to a change inthe operation of a timer.

The method can further comprise the step of storing an auto-slug settingrepresentative of whether at least one of the plurality of controllersis initiating a slug condition. A sleep setting representative of theinitiation of a sleep condition can be stored to serve as a referencefor further evaluation of a sleep condition. A jam settingrepresentative of a jam condition can be stored to serve as a referencefor further evaluation of a jam condition.

The method can further comprise the step of responding to a signalreceived that is representative of the presence of an object from anupstream zone. The signal relating to the presence of an object local toan upstream controller can be stored to serve as a reference for furtherevaluation of the presence of an object local to an upstream controller.The signal can be communicated to at least one adjacent downstreamcontroller representative of state of the upstream controller.

The method can further comprise the step of responding to a signalrepresentative of the presence of an object local to a downstreamcontroller. The signal relating to the presence of an object local to adownstream controller can be stored to serve as a reference forevaluation of a subsequent received signal relative to the presence ofan object local to a downstream controller. The signal can becommunicated to at least one adjacent upstream controller representativeof the state of the downstream controller.

The method can further comprise the step of responding to a signal froman adjacent downstream controller relating to the status of an objectdetector as a smart object detector. The signal can be communicated toat least one adjacent upstream controller representative of the state ofthe downstream controller as having a smart object detector.

The method can further comprise the step of responding to a signal froman adjacent upstream controller concerning the release of an object froman upstream zone. The method can further comprise the step ofdetermining whether the controller is adjacent to a downstreamcontroller. The signal can be communicated to at least one adjacentdownstream controller representative of the result of the evaluatingstep. The actuator corresponding to the controller local to the zone canbe operated in response to the received signal in order to actuate theactuator and operate the movement of objects in the zone local to thecontroller.

The method can further comprise the step of responding to a signalreceived that is representative of a change in a slug condition from atleast one upstream controller. The method can further comprise the stepof determining whether the controller is adjacent a downstreamcontroller. The signal can be communicated to at least one adjacentdownstream controller representative of the slug condition in the atleast one adjacent downstream controller. The slug condition can beupdated in the local controller in response to the received signal. Theslug condition can be communicated to at least one adjacent upstreamcontroller to update a slug condition in the at least one adjacentupstream controller.

The method can further comprise the step of responding to a signal froman adjacent downstream controller relating to presence of an objectlocal to the zone of the adjacent downstream controller. The signal canbe stored from the adjacent downstream controller representative of thepresence of the object local to the zone of the adjacent downstreamcontroller. The method can further comprise the step of responding to asignal received from at least one downstream controller representativeof a change in a slug condition. The signal from the at least onedownstream controller representative of the change in the slug conditioncan be stored to serve as a reference for evaluation of a subsequentreceived signal representative of a change in a slug condition. Themethod can further comprise the step of determining whether a jamcondition exists. The signal representative of the slug condition can becommunicated to at least one upstream controller to propagate the a slugcondition to the at least one upstream controller if the jam conditionis determined not to exist.

The method can further comprise the step of responding to a signalreceived from at least one downstream controller representative of a jamcondition. The signal representative of the jam condition can becommunicated to at least one upstream controller to propagate the jamcondition to the at least one upstream controller.

The method can further comprise the step of responding to the expirationof a sleep timer. The method can further comprise the step of storinginformation representative of the initiation of a sleep condition toserve as a reference for further evaluation of the sleep condition ofthe controller.

The method can further comprise the step of responding to the expirationof a jam timer. The method can further comprise the step of storinginformation representative of the activation of a jam condition to serveas a reference for further evaluation of the jam condition of thecontroller.

The method can further comprise the step of determining whether theoperable interconnections of the controller to at least one of theupstream controller and the downstream controller is in a ground state.A slug condition can be initiated in the controller if the detectingstep does not detect a ground state, or terminated in the controller ifthe detecting step does not detect a ground state.

The method can further comprise the step of responding to adetermination of whether a sleep mode is enabled. The method can furthercomprise the steps of determining whether the controller is a downstreamend controller if sleep mode is not enabled, and determining whether thecontroller is an upstream end controller if sleep mode is enabled. Themethod can further comprise the step of determining whether thecontroller and at least one upstream controller have detected thepresence of an object. A sleep condition can be activated and a sleeptimer can be deactivated if at least one of the controller and at leastone adjacent upstream controller detect the presence of an object in azone local to the at least one of the controller and the at least oneadjacent upstream controller. The method can further comprise the stepof determining whether a sleep condition is active if the controller andat least one adjacent upstream controller do not detect the presence ofan object in a zone local to the controller and at least one adjacentupstream controller. The method can further comprise the step ofdetermining whether a sleep timer is running if the sleep condition isnot active, and the step of at least one of resetting and activating thesleep timer if the sleep timer is not running. The method can furthercomprise the step of determining whether the controller is a downstreamend controller if the sleep timer is running, and the step ofdeactivating the actuator corresponding to the controller local to thezone if a sleep condition is active.

The method can further comprise the step of responding to adetermination of whether the controller is a downstream end controller,and the the step of determining whether a jam mode is enabled if thecontroller is not a downstream end controller.

The method can further comprise the steps of responding to adetermination of whether a jam mode is enabled, determining whether anobject is present in a zone local to the controller and an object is notpresent in either a first downstream zone and a second downstream zone,and determining whether a signal representative of a jam condition inthe first downstream controller has been received by the controller ifan object is not present in a zone local to the controller and an objectis present in both the first downstream zone and the second downstreamzone. The method can further comprise the steps of deactivating the jamcondition, sending a signal representative the jam condition to thefirst upstream controller, and deactivating the jam timer, if a signalrepresentative of an active jam condition has not been received from thefirst downstream controller, and sending a signal representative of aterminated slug condition, deactivating an auto-slug condition, andsending a signal representative of an activated jam condition to thefirst upstream controller if a signal representative of an activated jamcondition has been received from the first downstream controller. Themethod can further comprise the steps of determining whether a jamcondition exists if an object is present in the zone local to thecontroller and an object is not present in at least one of the firstdownstream zone and the second downstream zone, and whether a jam timeris running if a jam condition does not exist. The method can furthercomprise the steps of activating the jam timer if the jam timer is notrunning, and determining whether a slug mode is enabled if the jam timeris running. The method can further comprise the step of sending a signalrepresentative of a deactivated slug condition and a deactivatedauto-slug condition local to the controller, and sending a signalrepresentative of an activated jam condition to the first upstreamcontroller if a jam condition is detected.

The method can further comprise the steps of responding to adetermination of whether a slug mode is enabled, determining whether acurrent slug condition exists if slug mode is enabled, and determiningwhether auto-slug mode is enabled if slug mode is not enabled. Themethod can further comprise the steps of determining whether auto-slugmode is enabled if the current slug condition does not exist, andactivating the actuator corresponding to the controller local to thezone if the slug condition does exist.

The method can further comprise the steps of responding to adetermination of whether auto-slug mode is enabled, determining whethera first downstream object detector does not detect an object ifauto-slug mode is not enabled, and determining whether an auto-slugdelay timer has been started if auto-slug mode is enabled. The methodcan further comprise the steps of determining whether a first downstreamobject detector and a second downstream object detector each do notdetect an object if the auto-slug delay timer is not running, sending asignal to a first upstream controller representative of a stop auto-slugcondition if the first downstream object detector or the seconddownstream object detector each do not detect the object, and activatingthe actuator corresponding to the controller local to the zone if thefirst downstream object detector and the second downstream objectdetector each do not detect an object. The method can further comprisethe steps of determining whether the auto-slug delay timer has expiredif the auto-slug delay timer has been started, and activating theactuator corresponding to the controller local to the zone if theauto-slug delay timer has expired. The method can further comprise thestep of sending a signal to a first upstream controller representativeof a start auto-slug condition.

The method can further comprise the steps of responding to adetermination of a change in state of a first downstream object detectorand activating the actuator corresponding to the controller local to thezone if the first downstream photo-eye is clear. The method can furthercomprise the step of deactivating the actuator corresponding to thecontroller local to the zone if the first downstream object detectordoes not detect an object.

The method can further comprise the steps of activating the particularone of the plurality of actuators in response to a signal initiated bythe at least one event logic element, performing a plurality of eventlogic elements for evaluating and controlling the position of the atleast one object in the plurality of zones, and transmitting a signalrelating to the position of the at least one object to the at least oneof the adjacent upstream controller and the adjacent downstreamcontroller. The method can further comprise the step of determiningwhether to actuate a particular one of the actuators responsive to ahierarchy process called by an event logic element based on theenablement of at least one function mode, wherein the at least onefunction mode comprises at least one of a sleep mode, a downstream endmodule mode, a jam mode, a slug mode, an auto-slug mode, and a valveoperation mode.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of an embodiment comprising a portion of aconveyor system comprising microprocessor-based networkable zone controlmodules according to the invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a close-up perspective view of a networkable zone controlmodule as shown in FIG. 1.

FIG. 4 is a configuration drawing of a control system for the conveyorsystem shown in FIG. 1 showing a series of networked zone controlmodules according to the invention interconnected to a prior artserver-based system via an interpreter also according to the inventionvia conventional interconnections.

FIG. 5 is a configuration drawing of a first alternative control systemfor the conveyor system shown in FIG. 1 showing simply a series ofinterconnected zone control modules according to the inventionterminated at upstream and downstream ends by terminators.

FIG. 6 is a configuration drawing of a second alternative control systemfor the conveyor system shown in FIG. 1 including a master configurationmodule having mode-select switches.

FIG. 7 is a representation of the master configuration module shown inFIG. 6 illustrating the position of the mode-select switches forselected configuration functions.

FIG. 8 is a drawing of a portion of the conveyor system shown in FIG. 1illustrating an identification convention for a series of interconnectedzone control modules according to the invention.

FIG. 9 is a flow chart drawing of a portion of a microprocessor-basedcollection of event logic elements for evaluating information receivedby a zone control module in the system shown in FIG. 1.

FIG. 10 is a flow chart drawing of a first event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a local photo-eye event.

FIG. 11 is a flow chart drawing of a second event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a photo-eye delay timer event.

FIG. 12 is a flow chart drawing of a third event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating an auto-slug initiation event.

FIG. 13 is a flow chart drawing of a fourth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating an auto-slug termination event.

FIG. 14 is a flow chart drawing of a fifth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating an auto-slug delay timer event.

FIG. 15 is a flow chart drawing of a sixth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a second upstream photo-eye event.

FIG. 16 is a flow chart drawing of a seventh event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a first upstream photo-eye event.

FIG. 17 is a flow chart drawing of an eighth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a first downstream photo-eye event.

FIG. 18 is a flow chart drawing of a ninth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a smart photo-eye event.

FIG. 19 is a flow chart drawing of a tenth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a release message event.

FIG. 20 is a flow chart drawing of an eleventh event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating an upstream slug message event.

FIG. 21 is a flow chart drawing of a twelfth event logic element of themicroprocessor-based collection of event logic elements shown in FIG. 9for evaluating a second downstream photo-eye event.

FIG. 22 is a flow chart drawing of a thirteenth event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating a downstream slug message event.

FIG. 23 is a flow chart drawing of a fourteenth event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating an external jam event.

FIG. 24 is a flow chart drawing of a fifteenth event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating a sleep timer event.

FIG. 25 is a flow chart drawing of a sixteenth event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating a jam timer event.

FIG. 26 is a flow chart drawing of a seventeenth event logic element ofthe microprocessor-based collection of event logic elements shown inFIG. 9 for evaluating a fourth photo-eye pin event.

FIG. 27A is a flow chart of a first portion of a hierarchy logicprocessof the microprocessor-based collection of event logic elements shown inFIG. 9.

FIG. 27B is a continued flow chart of a second portion of a hierarchylogic process of the microprocessor-based collection of event logicelements shown in FIG. 9.

FIG. 28 is a drawing of an organizational arrangement of configurations,timers, and variables for processing by the microprocessor shown in FIG.3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, and to FIGS. 1-3 in particular, a preferredembodiment of the invention comprises a conveyor system 10 comprising aseries of rollers 12 rotatably mounted between a back rail 14 and afront rail 16 in a conventional manner. The rollers 12 can be operablyorganized into roller units 13, or “zones,” comprising a selected numberof rollers 12 in which the rollers 12 in a zone 13 will operate inconcert. A continuous-loop drive belt 18 moves beneath the rollers 12,and is selectively brought into contact with a selected zone 13 by adrive plate 36 which is raised against an overlying zone 13 by apneumatic actuator 38. A plurality of interconnected zone controlmodules 20 are mounted in a suitable fashion, such as by a clipintegrated into the zone control module 20 or a threaded fastener, atregular intervals to the front rail 16, with each zone control module 20operably associated with a specific zone 13. It will be understood thatthe particular mounting arrangement of the modules 20 to the rails 14,16 is not critical to the invention, and any suitable arrangement willbe apparent to one skilled in the art.

Each zone control module 20 is interconnected with an associatedphoto-electric sensing device 22, such as an optical sensor or aphoto-eye, in a peer-to-peer network according to the invention. Theoptical sensors 22 are mounted to the front rail 16 through a suitablesensor mount, such as a bracket, and are adapted to detect the physicalpresence of an object, such as a carton (shown by example by referencenumerals 30, 32, 34) being conveyed along the conveyor system 10. Eachoptical sensor 22 is provided with a mating receiver 24 mounted to theback rail 14 so that an optical signal or photoelectric beam, shown inFIG. 1 as a sensor beam 26, is transmitted between the optical sensor 22and the receiver 24. The optical sensor 22 and the receiver 24 are shownoperating in a direction perpendicular to the direction of travel of theconveyor system 10, but the operation direction shown in FIG. 1 shallnot be construed as limiting on the invention and can be skewed relativeto the direction of travel of the conveyor system 10 without departingfrom the scope of the invention. The zone control modules 20 arecommunicably interconnected by control cables 28 adapted for thetransmission of digital information, including information from theoptical sensors 22, among the zone control modules 20. The controlcables 28 also supply power to the optical sensors 22 and the zonecontrol modules 20.

Selected optical sensors 22 can be programmed as “smart photo-eyes” forreporting package movement conditions along the conveyor system 10 to aninstallation computer system 68. Whenever the photoelectric beam fromthe smart photo-eye is interrupted, the zone control module associatedwith the smart photo-eye sends a signal to the main computer or server68. This information, combined with similar information from the othersmart photo-eyes provides real-time reporting on the available capacityof the conveyor system 10. Alternatively, the computer 68 canperiodically request information from each smart photo-eye according toa preselected schedule.

In the preferred embodiment, the zone control module 20 comprises ahousing 40 adapted to enclose a solenoid-operated pneumatic valve (notshown) and a digital microprocessor (not shown). The housing 40 isprovided with suitable fittings for fluid connection of a common airline 29 interconnecting adjoining zone control modules 20 as shown inFIG. 1, and fluidly connecting the zone control modules 20 to a sourceof pressurized air (not shown). The pneumatic valve is fluidly connectedto the air line 29 and to the pneumatic actuator 38 via a pneumaticactuator outlet 50. The pneumatic valve fluidly interconnects the airline 29 with the pneumatic actuator 38 for selectively activating anddeactivating the pneumatic actuator 38. A pneumatic actuator exhaustport 52 is also fluidly connected to the pneumatic valve for selectivelyexhausting air from the pneumatic actuator 38 when the pneumaticactuator 38 is deactivated.

There are several terms used herein which may have a further definitionbeyond their ordinary meaning and, thus, are set forth below in Table 1.TABLE 1 TERM DEFINITION ACCUMU- A condition wherein, if a LOCAL MODULEreceives an LATION accumulation signal from DS1, the pneumatic valve isturned OFF. AUTO- An operational mode in which a zone control moduleSLUG which is pre-configured to accept/generate an AUTO-SLUG signal willactivate a LOCAL pneumatic valve when the LOCAL MODULE generates orreceives an AUTO-SLUG signal from a downstream zone control module. DS1First zone control module removed from the LOCAL MODULE in the directionof conveyor travel. DS2 Second zone control module removed from theLOCAL MODULE in the direction of conveyor travel. EXTREME A zone controlmodule which can be configured for DOWN- an auto detection condition oran installation STREAM system-configured condition. For auto detection,a MODULE termination plug is placed on the uncoupled cable (EDM) end.This protects the connectors and attaches the signal wires to ground. Bygrounding the signal wires, the EDM module automatically detects itsunique location and responds to events appropriately. For aninstallation system configuration, the EDM module is mapped in thesystem software. During initial start up, the EDM module is configuredfor its unique location and responds to events appropriately. The EDMmodule also releases and accumulates as dictated by signals transmittedfrom the installation computer system. JAM An operational modereflecting one or more jammed packages so that a LOCAL P.E. remains in a“blocked” state, the DSI and DS2 P.E.s remained “unblocked,” and theLOCAL VALVE is in an “on” state after a predetermined amount of time,i.e. the JAM TIMER. If the JAM TIMER is allowed to expire, the LOCALVALVE is left turned “on” in an attempt to “clear” the jam, and theLOCAL MODULE passes a JAM “ON” signal to US1, terminating any slug orauto-slug operations upstream, stopping moving product. Normal operationbegins when the LOCAL P.E. is clear. If the LOCAL MODULE is therecipient of a JAM signal from DS1, the LOCAL MODULE turns the LOCALVALVE “off” and begins accumulation. This accumulation propagatesupstream. If a LOCAL P.E. change in state does not occur within the JAMTIMER, any slug or auto-slug operations are terminated, and a JAM signalis transmitted to US1 and the interpreter. If the LOCAL P.E. clears,then a JAM CLEARED signal is transmitted to US1 and the interpreter. Ifa JAM signal is received from DS1, then the LOCAL MODULE enters anaccumulation condition. If a JAM CLEARED signal is received from US1,then the LOCAL MODULE enters a release condition. JAM A predeterminedamount of time, T_(j), to detect a TIMER JAM by monitoring the LOCALP.E., and the DS1 and DS2 P.E.s. LOCAL A zone control module under theinfluence of selected zone control modules located immediately upstreamand downstream, i.e. US1, US2, DS1, DS2. P.E. Photo-eye; aphoto-electric, product sensing device. RELEASE A condition of theExtreme Downstream Module (EDM) wherein, if a RELEASE signal is receivedfrom US1, the LOCAL VALVE is turned “on.” SLEEP An operational mode inwhich, after a MODE predetermined amount of time, i.e. the SLEEP TIMER,the LOCAL VALVE is turned “off” until a WAKE-UP signal is received. TheSLEEP TIMER is started when the LOCAL, US1, and US2 P.E.s are cleared.If the P.E.s change state, the SLEEP TIMER is reset. If the SLEEP TIMERexpires prior to a change in the P.E. state, the LOCAL VALVE is turned“off.” SLEEP A predetermined amount of time, T_(s), to wait TIMER beforeturning the LOCAL VALVE “off.” SLUG An operational mode in which aplurality of zone control modules are signaled to activate their VALVESto convey moving product irrespective of P.E. inputs. SMART Anoperational mode in which, if a zone control SENSOR module is designatedas a SMART SENSOR, (P.E.) the LOCAL P.E. status is transmitted to theinterpreter for diagnostic purposes. US1 The first zone control moduleremoved from the LOCAL MODULE in the direction opposite to the directionof conveyor travel. US2 The second zone control module removed from theLOCAL MODULE in the direction opposite to the direction of conveyortravel. VALVE A solenoid valve incorporated into each zone controlmodule. The circuit board logic turns the VALVE “on” or “off” based onexternal inputs. WAKE-UP A signal that is transmitted to the LOCALMODULE from US1 or US2 when the US1 or US2 P.E.s become blocked. Thissignal “wakes up” the LOCAL MODULE and returns the LOCAL MODULE tonormal operation. A LOCAL MODULE P.E. can also create a WAKE-UP signalwhen it indicates a “blocked” condition.

A microprocessor comprises a programmable digital processor in the zonecontrol module 20 operatively connected to a downstream control cable 42and an upstream control cable 46 for operably interconnecting adjacentzone control modules 20 in series, as shown in FIG. 1. Themicroprocessor can process information in a conventional manner, such asin 8-bit bytes, each byte conveying information as to the type ofinformation processed, the message or command processed, and a counter.For example, a first byte can identify the type of message being sent. Asecond byte can contain the actual message content. The third byte issimply a counter that is initiated at some predetermined value (such as0 or 1) and incremented by each zone control module 20 that passes themessage along through the number of interconnected zone control modules20 in a contiguous series. The microprocessor is preferablypre-programmed to perform a logic process, shown in FIGS. 9-26, and ahierarchy process shown in FIGS. 27A and 27B. Further description of themessaging protocol employed by peer-to-peer networked zone controlmodules 20 will be provided in greater detail below.

There are various communications protocols employed during operableinterconnection of the zone control modules 20, the interpreter 60 and amaster/server computer 68 (such as that typically used in a Field Busenvironment), as shown in FIG. 4.

A master/slave concept is used to control communications between thevarious system elements:

-   -   master/server installation computer 68 or temporarily installed        computers 74 to the interpreters 60,    -   interpreters 60 to zone control modules 20, or    -   zone control module 20 to zone control module 20,        with the master/server installation computer 68 serving as the        ultimate “master” in the above listed combinations. The master        in this master/slave concept is always upstream of the slave.        For example, the interpreter 60 is a slave to either the        master/server installation computer 68 or the temporarily        installed computer 74 while the most upstream zone control        module 20 is a slave to the interpreter 60. Additionally, a        downstream zone control module 20 is the slave to an upstream        zone control module 20.

A baud clock can be generated by the master and sent to the slave tosend or retrieve data/status information. The data signal level ischanged by the master or slave during the logic “low” level of the baudclock and read by the master or slave during the logic “high” level ofthe baud clock.

With respect to the zone control modules 20 and the master/slaveimplementation, an upstream end point of a series of interconnected zonecontrol modules 20 can be determined by the absence of the baud clock.To determine a downstream endpoint, an upstream master control modulepolls the downstream zone control module (slave) for acknowledgment(ACK) as is further described below. If no ACK signal is received fromthe downstream endpoint zone control module (a slave), the masterupstream zone control module determines that zone control module to bethe downstream endpoint. If an ACK is received from a particular polledzone control module, the endpoint determination is passed to the nextsuccessive downstream zone control module via the master/slave concept.

The upstream master zone control module can send any size data packets,and terminates with an end-of-signal marker (e.g., such as an ACKsignal). The ACK signals the slave zone control module that the masterzone control module has finished transmitting and has set the data lineas an input and that it is available for the slave zone control moduleto transmit its data/status. A slave zone control module can send anysize data packet to the master zone control module ending with anend-of-message marker (e.g., the last data item being an ACK). The ACKsignal not only signals the upstream master zone control module that adownstream zone control module is present, it also signals that thedownstream slave zone control module is no longer driving the data lineand the upstream master zone control module can now have output driveaccess of it. If no ACK is received from a zone control module, it isassumed that a downstream zone control module is not present and themaster zone control module is at a downstream endpoint.

Several examples of data protocols will now be described with theunderstanding that they are by example only, and that othercommunications protocols or methods can be used without departing fromthe scope of this invention.

With respect to the data protocol used in these examples, data istransmitted in the following example format. There is an initial startbit followed by eight data bits (bit 7 is used to determine a packettype, e.g., if bit 7=1 it is a control byte, if bit 7=0, it is a databyte), and is terminated with one stop bit. The following tableidentifies some example codes used in the protocol: Data Definition FFPacket Start AA ACK 00-7F Data

Using the above-described communication codes, several example messageformats will now be described for communication between a computer 68,74, the interpreter 60 and the various zone control modules 20.

The following table describes communication from the interpreter 60 tothe various zone control modules 20. Configuration Packet: FromInterpreter 60 to Zone Control Modules 20 Byte 1 Header(0x81) Byte 2Length # bytes in packet not including header or length but includingchecksum. Byte 3 Node Number (ADDRESS). If MSB is set then address is“ALL” nodes. Byte 4 Bit0 Sleep Enabled (Y/N) Bit1 Jam Enabled (Y/N) Bit2External Slug Enabled (Y/N) Bit3 Auto Slug Enabled (Y/N) Bit4 Smart Eye(Y/N) Bit5 Sleep Timer Length to Follow (Y/N) Bit6 Jam Timer Length toFollow (Y/N) Bit7 Slug Line (Y/N) Byte 5 Sleep OR Jam timer value if atleast 1 timer selected. If neither selected, no data byte. Byte 6 Jamtimer value if both selected. If only one or neither, no data byte. ByteN Checksum. 1 byte sum of all bytes excluding header and checksum.

Status Packet: From Nodes to Int. Controller Byte 1 Header (0x80) Byte 2Length. No. of bytes in packet not including header or length butincluding checksum. Byte 3 Node no (e.g., “Address”). Byte 4 Data. Byte1Bit0 PhotoEye (0 = off, 1 = on) Bit1 Solenoid (0 = off, 1 = on) Bit2-7Available for use (all 0's by default) Byte 5 Checksum. 1 byte sum ofall bytes excluding header and checksum.

The following table describes a configuration communication between anexternal computer 68, 74 and the various zone control modules 20.Configuration Packet: From External Computer 68, 74 to Zone ControlModules 20 Byte 1 Header(0x81) Byte 2 Length. No. of bytes in packet notincluding header or length but including checksum. Byte 3 Node number(e.g., “Address”). If MSB is set then address is “ALL” nodes. Byte 4Data. Bit0 Sleep Enabled (Y/N) Bit1 Jam Enabled (Y/N) Bit2 External SlugEnabled (Y/N) Bit3 Auto Slug Enabled (Y/N) Bit4 Smart Eye (Y/N) Bit5Slug Line (Y/N) Bit6 Available (defaults to 0) Bit7 Available (defaultsto 0) Byte 5 Sleep OR Jam timer value if at least 1 timer selected. Ifneither selected, no data byte. Byte 6 Jam timer value if both selected.If only one or neither, no data byte. Byte N Checksum. 1 byte sum of allbytes excluding header and checksum.

The following table describes a configuration request communicationbetween an external computer 68, 74 and the various zone control modules20. Configuration Request Packet: From External Computer 68, 74 to ZoneControl Modules 20 Byte 1 Header (0x81) Byte 2 Length. No. of bytes inpacket not including header or length but including checksum. Byte 3Node number (e.g., “Address”). If MSB is set then address is “ALL”nodes. Byte 4 Data. Bit0 0 Bit1 0 Bit2 0 Bit3 0 Bit4 0 Bit5 0 Bit6 1Bit7 1 Byte 5 Checksum. 1 byte sum of all bytes excluding header andchecksum.

The following table describes a configuration request communicationbetween an the various zone control modules 20 and an external computer68, 74 to indicate the status of a particular zone control module 20.Status Packet: From Zone Control Modules 20 to External Computer 68, 74Byte 1 Header (0x80) Byte 2 Length. No. of bytes in packet not includingheader or length but including checksum. Byte 3 Node no. (e.g.,“Address”). Byte 4 Data. Bit0 PhotoEye (0 = off, 1 = on) Bit1 Solenoid(0 = off, 1 = on) Bit2 Sleep Enabled (Y/N) Bit3 Jam Enabled (Y/N) Bit4External Slug Enabled (Y/N) Bit5 Auto Slug Enabled (Y/N) Bit6 Smart Eye(Y/N) Bit7 Slug Line (Y/N) Byte 5 Checksum. 1 byte sum of all bytesexcluding header and checksum

The zone control module 20 also comprises a data and memory structurecomprising configuration settings 340, timers 342, and variables 344illustrated by example in FIG. 28. The configuration settings 340 cancomprise a sleep setting 346, a jam setting 348, an external slugsetting 350, an auto-slug setting 352, and a smart photo-eye setting354. These settings are comprised of binary data (0, 1) eitherpre-programmed into the microprocessor or transferred to themicroprocessor via the installation computer system 68, a temporarilyinstalled computer 74, or a wireless device (e.g. a PDA) via an infraredport with the use of the interpreter 60. A set of configuration settingswitches may also be used to input the desired settings to themicroprocessor as shown in FIG. 6 as 82. The timers 342 can comprise asleep timer 356 and a jam timer 358. The timers operate in aconventional manner and need not be described in great detail beyond theevents which trigger the timers' initiation and events triggered by theexpiration of the timers. The variables 344 can comprise a localphoto-eye register 360, a first downstream photo-eye register 362, asecond downstream photo-eye register 364, a sleep register 366, a jamregister 368, a local auto-slug register 370, an external auto-slugregister 372, and a (controller) slug register 374. These registerspreferably comprise simple on-off devices or standard RAM locations forstoring “activated-deactivated” or “enabled-disabled” information.

The zone control modules 20 can also be provided with additional timers,including a photo-eye delay timer, and auto-slug delay timer, a sleeptimer, and a jam timer. The photo-eye delay timer is initiated when anoptical sensor 22 detects the presence of a package. Depending uponwhether the optical sensor 22 continues to detect the presence of apackage or not before the delay timer expires, the zone control module20 communicates one or more messages to the upstream and/or downstreamzone control modules 20 based upon a collection of event logic elementshereinafter described. The auto-slug delay timer is initiated when azone control module 20 receives a message from the immediately followingdownstream zone control module to initiate an auto-slug function. Thesleep timer is initiated when the zone control module 20 activates thepneumatic actuator 38, which activates a zone 13. If the zone controlmodule 20 has not received a message from another zone control module,or has not detected the presence of a package, before the expiration ofthe sleep timer, the zone control module 20 enters sleep mode anddeactivates the zone 13. The jam timer is initiated when the zonecontrol module 20 detects the presence of a package and the downstreamzone control modules do not detect the presence of packages. If the jamtimer expires without a change in this condition, the zone controlmodule 20 communicates a message to upstream zone control modules toprevent the further transfer of packages from upstream.

The downstream control cable 42 can be terminated in a downstreamconnector 44. The upstream control cable 46 can be terminated in anupstream connector 48 adapted to connect to the downstream connector 44of an adjacent zone control module 20, such as through mating male andfemale connectors, to communicatively connect the zone control modules20 in series when it no form of the interpreter 60 is used (FIG. 5). Theconnectors 44, 48 comprise conventional 4-pin connectors.

An optical sensor input 54 on the zone control module 20 is used toelectrically interconnect the zone control module 20 with its associatedoptical sensor 22.

The operational control configuration of the conveyor system 10 can bemodified to provide different levels of operational control. Referringto FIG. 4, the zone control modules 20 can be connected in series toterminate at the downstream end of the conveyor system 10 in adownstream cable terminator 62. At the upstream end, the zone controlmodules 20 terminate in an interpreter module 60, which is adapted tocommunicate with a wireless personal digital assistant (PDA) 64, or oneor more networked computer stations 68 through a field bus 72 connectedto a gateway module 66 which is connected to the interpreter module 60through a field bus 70 using standard network protocols, such as RS-232or a field bus protocol (as is commonly known in the material handlingindustry). Alternatively, the interpreter 60 can be connected to alaptop computer 74 using standard network protocols 76, such as RS-232.This system enables selected zone control modules 20 to be individuallyprogrammed by the PDA 64, the installation computer stations 68, or thelaptop computer 74.

As shown in FIG. 5, an alternate configuration utilizes an upstreamcable terminator 80 at the upstream termination of the zone controlmodules 20, and a logic controller 78 interconnected with the downstreamzone control module 20 for controlling the discharge zone as packagesleave the zone shown in FIG. 5 to another handling area in the conveyorsystem. As shown in FIG. 6, in yet another configuration, the upstreamcable terminator 80 is replaced with a master configuration module 82comprising a plurality of mode-select switches 84. Configurationsettings on the master configuration module 82 are propagated to thenetworked zone control modules 20 through a configuration message in theprotocol described herein.

Referring now to FIG. 7, the master configuration module 82 can comprisea plurality of mode-select switches controlling a selected function. Itis to be understood that the master configuration module 82 comprises aportion of the interpreter 60 logic for propagating settings to the zonecontrol modules 20, without departing from the scope of this invention.For example, the first sleep switch 90 and the second sleep switch 92control four sleep operations. With both switches 90, 92 in the “off”position (up as viewed in FIG. 7), the sleep function will bedeactivated. With the first sleep switch 90 in the off position and thesecond sleep switch 92 in the “on” position, the sleep function will beactivated after the expiration of a first interval, such as 2 seconds.With the first sleep switch 90 in the on position and the second sleepswitch 92 in the off position, the sleep function will be activatedafter the expiration of a second interval, such as 5 seconds. Finally,with both switches 90, 92 in the on position, the sleep function will beactivated after the expiration of a third interval, such as 8 seconds .

The jam switch 94 controls a hereinafter-described jam detectionoperation. With the jam switch 94 in the off position, the jam detectionfunction is deactivated. With the jam switch 94 in the on position, thejam detection function is activated. Similarly, the external slug switch96 controls a hereinafter-described external slug operation. With theexternal slug switch 96 in the off position, the external slug functionis deactivated. Conversely, with the external slug switch 96 in the onposition, the external slug function is activated. Finally, theauto-slug switch 98 controls a hereinafter described auto-slugoperation. With the auto-slug switch 98 in the off position, theauto-slug function will be deactivated. With the auto-slug switch 98 inthe on position, the auto-slug function will be activated. Activating aswitch in the master configuration module 82 sets all zone controlmodule 20 to perform the same function. The jam, external slug, andauto-slug functions will be further described herein with respect toFIGS. 9-28.

FIG. 8 is a drawing depicting a portion of the conveyor system 10comprising rollers 12 organized into zones 13 controlled by associatedzone control modules 20 and optical sensors 22. Five zone controlmodules 20 are shown interconnected as previously described. However, itshould be understood that the typical conveyor system 10 will comprise aplurality of zones 13, corresponding zone control modules 20, andoptical sensors 22. Nevertheless, the logic for the conveyor controlsystem is structured around an exemplary plurality of zone controlmodules, or “neighborhood,” comprising five zone control modules 20comprising a local zone control module 110, a first downstream zonecontrol module 112 (DS1), a second downstream zone control module 114(DS2), a first upstream zone control module 116 (US1), and a secondupstream zone control module 118 (US2). The five zone control modules110-118 communicate with each other through the control cables 28 aspackages travel along the conveyor system 10.

As shown in FIG. 8A, each zone control module 20 is a local zone controlmodule 110 within a neighborhood of five zone control modules. Each zonecontrol module 110 processes one or more of the event logic elementsaccording to a collection of event logic elements shown in FIG. 9 anddescribed hereinafter. With respect to an event logic element beingprocessed by a particular zone control module 110, referred to as the“local” zone control module (L), the two immediately downstream zonecontrol modules 20 and the two immediately upstream zone control modules20 comprise a particular zone control module's “neighborhood,” and areidentified as the first downstream zone control module 112 (DS1), thesecond downstream zone control module 114 (DS2), the first upstream zonecontrol module 116 (US1), and the second upstream zone control module118 (US2). However, each of the two downstream zone control modules 112(DS1), 114 (DS2) and the two upstream zone control modules 116 (US1),118 (US2) is also a local zone control module 110 with respect to anevent logic element being processed by that zone control module, withits own neighborhood of downstream and upstream zone control modules112-118. Thus, as shown in FIGS. 8 and 8A, a particular zone controlmodule 20 can simultaneously comprise a local zone control module 110(L), a first downstream zone control module 112 (DS1), a seconddownstream zone control module 114 (DS2), a first upstream zone controlmodule 116 (US1), and a second upstream zone control module 118 (US2) asdetermined by its processing of an event logic element, or theprocessing of an event logic element by either of the two downstreamzone control modules 112 (DS1), 114 (DS2) or the two upstream zonecontrol modules 116 (US1), 118 (US2).

For convenience, the optical sensor 22 associated with a specific zonecontrol module 20 will be referred to by the designation of that zonecontrol module. For example, the optical sensor 22 associated with alocal zone control module 110 will be referred to as the local opticalsensor or photo-eye, and the optical sensor 22 associated with thesecond downstream zone control module 114 (DS2) will be referred to asthe second downstream optical sensor or photo-eye.

The conveyor system 10 can operate in one of several modes, referred toherein as accumulation, slug, auto-slug, jam, and sleep modes. Othermodes are conceivable to those skilled in the operation of conveyors andare technically feasible in the embodiment of this invention.

In accumulation mode, the local zone control valve is activated if theDS1 photo-eye indicates that the DS1 zone is “clear.” Conversely, thelocal zone control valve is deactivated if the DS1 photo-eye indicatesthat the DS1 zone is “not cleared.”

In slug mode, all zones 13 are activated to transfer packages along theconveyor regardless of inputs from the photo-eye 22 (typically used torapidly advance one or more objects along a conveyor system having alength of unoccupied space).

In auto-slug mode, a zone control module 20 which is configured toaccept or generate an auto-slug signal will turn a local zone controlvalve on, thereby activating the zone 13 associated with the local zonecontrol valve, when the local zone control module generates its ownauto-slug signal or receives an auto-slug signal from a downstream zonecontrol module.

Jam detection mode responds to the condition that occurs when a packageis unable to travel down the conveyor system 10, such as when packagesare jammed in such a way as to prevent their further movement. In such acondition, the photo-eye associated with a local zone control modulesignals the presence of a package, the downstream photo-eyes fail todetect a package, and the local zone control valve remains in anactivated state after a predetermined amount of time has expired,referred to as the jam timer. If the jam timer expires, the local zonecontrol valve is left activated to possibly “clear” the jam condition,and the local zone control module passes a “jam on” signal to the firstupstream zone control module, disabling any previously enabled slug orauto-slug condition, thereby stopping additional packages from travelingdown the conveyor into the jammed zone. Normal conveyor operationresumes when the local photo-eye no longer detects the presence of apackage.

In sleep mode, the zone control module deactivates the local zonecontrol valve after a predetermined amount of time has expired (sleeptimer), during which the local photo-eye 110 and its associated upstreamphoto-eyes (US1, US2) 116, 118 are “cleared.” The local zone controlvalve remains deactivated until a change in photo-eye status is receivedby the local zone control module 110 (L) from the second upstream zonecontrol module 118 (US2), triggering the performance of the hierarchyprocess, consistent with the event logic element 128 shown in FIG. 15,and causing the local zone control module 110 (L) to “wake up” pursuantto hierarchy process steps 258 and 260 shown in FIG. 27A. A “wake-up”signal is also generated pursuant to the heirarchy process steps 258,260 if a package is placed in the path of a local photo-eye 110.

FIG. 9 illustrates a collection of event logic elements which each zonecontrol module 20 performs whenever it undergoes an event, such as asignal from the photo-eye, or a signal from an upstream or downstreamzone control module. Each event initiates the performance of event logicelements associated with that event.

For example, an event may comprise a change in the local photo-eyecondition, identified in FIG. 9 as the event 120, or the expiration of adelay timer, identified in FIG. 9 as the event 126. An event may alsocomprise the receipt of a signal from a remote zone control modulecorrelating to a change in the photo-eye condition associated with thatzone control module, such as a change in the photo-eye condition of thefirst upstream zone control module, identified in FIG. 9 as the event130. Each of these events initiates the performance of event logicelements which are illustrated in FIGS. 10-26. The event logic elementsassociated with events 120, 122, 124, 126, 128, 130,132, 140, 142, 144,146, 148, and 150 can further initiate the performance of a hierarchyprocess, shown in FIGS. 27A and 27B. For purposes of description, thenumbering of the event logic elements corresponds with the numbering ofthe events in FIG. 9 as shown below in Table 2. TABLE 2 REFERENCE FIG.EVENT FUNCTION NO. NO. Local P.E. Process local photo- 120 10 eye eventP.E. DELAY Process photo-eye 122 11 TIMER expired delay timer eventStart A-SLUG Process auto-slug 124 12 received from DS1 initiation eventStop A-SLUG Process auto-slug 125 13 received from DS1 termination eventA-SLUG DELAY Process auto-slug 126 14 TIMER expired delay timer event ΔUS2 P.E. Process second 128 15 upstream photo-eye status change event ΔUS1 P.E. Process first 130 16 upstream photo-eye status change event ΔDS1 P.E. Process first 132 17 downstream photo- eye status change eventSmart P.E. (x) Process smart 134 18 received from DS1 photo-eye eventRelease message Process release 136 19 (ON/OFF) received message eventfrom US1 SLUG message Process upstream 138 20 (ON/OFF) received slugmessage event from US1 Δ DS2 P.E. Process second 140 21 downstreamphoto- eye status change event SLUG message Process downstream 142 22(ON/OFF) received slug message event from DS1 External JAM (x) Processexternal jam 144 23 (ON/OFF) received event from DS1 SLEEP TIMER Processsleep timer 146 24 expires event JAM TIMER Process jam timer 148 25expires event 4th P.E. PIN Process fourth 150 26 photo-eye pin event

Referring now to FIGS. 9 and 10, the first event logic element 120evaluates the status of the local photo-eye associated with the localzone control module 110 (i.e. the zone control module responding to anevent). The event logic element 120 first evaluates whether the localphoto-eye is blocked (decision node 152) by a package. If it is, aphoto-eye delay timer is started (step 154), the event logic elementterminates, and the next event (event 122 in this example) is evaluated.A slight delay in the recognition of a blocked local photo-eyeaccomplishes two functions: 1) it increases the efficiency of the systemby decreasing the gap between packages, and 2) it decreases the numberof cycles of the local zone control module valve, thereby increasing thelongevity of the entire system. If the photo-eye is not blocked, thephoto-eye delay timer is stopped (step 155), and the local photo-eyecondition, i.e. unblocked (0) or blocked (1), is stored in the zonecontrol module's memory (local photo-eye register 360) (step 156) inorder to serve as a baseline for comparison of future photo-eyeconditions. The event logic element then evaluates whether the smartphoto-eye function is enabled (decision node 158) for the localphoto-eye in order to control the flow of information from the localphoto-eye back to the PDA 64, the networked computer stations 68, or thelaptop computer 74. If it is, that information is transmitted to thefirst upstream zone control module 116 (US1) (step 160) as a uniquephoto-eye location (x) with photo-eye status to be propagated upstreamto the interpreter 60. Additionally, the local photo-eye status istransmitted to the first upstream zone control module 116 (US1) asinformation from a first downstream photo-eye (DS1) (step 162). If it isnot, the local photo-eye status is transmitted solely to the firstupstream zone control module 116 (US1) as information from a firstdownstream photo-eye (DS1) (step 162). The event logic elementterminates with the performance of a hierarchy process (step 164),described hereinafter, which determines whether the actuator 38 will beactivated or deactivated based on the configuration hierarchy of thesystem. After the performance of the hierarchy process in FIGS. 27A-B,the next event (event logic element 122) in the collection of eventlogic elements is evaluated.

Referring now to FIGS. 9 and 11, the second event logic element 122evaluates whether the photo-eye delay timer has expired. The expirationof the photo-eye delay timer indicates that a package has been conveyedinto the local zone for a preselected length of time, to be treated as ablocked photo-eye condition. This condition is conveyed upstream inorder to control the conveying of packages to the subject zone. Thelocal photo-eye status is first stored in memory (local photo-eyeregister 360) (step 166) in order to serve as a baseline for comparisonof future photo-eye conditions, and the event logic element evaluateswhether the smart photo-eye function is enabled as indicated by thesmart photo-eye setting 354 (decision node 168) for possible propagationupstream to the interpreter 60 in order to control the flow ofinformation from the local photo-eye back to the PDA 64, the networkedcomputer stations 68, or the laptop computer 74. If it is, thatinformation is transmitted to the first upstream zone control module 116(US1) as a message in the protocol described herein (step 170), and thelocal photo-eye status is transmitted to the first upstream zone controlmodule 116 (US1) as information from a first downstream photo-eye (DS1)(step 172). If it is not, the local photo-eye status is transmitted tothe first upstream zone control module 116 (US1) as information from afirst downstream photo-eye (DS1) (step 172). The event logic elementterminates with the performance of a hierarchy process (step 174),described hereinafter. After the performance of the hierarchy process,the next event (event logic element 124) in the collection of eventlogic elements is evaluated.

Referring now to FIGS. 9 and 12, the third event logic element 124evaluates a message received from the first downstream zone controlmodule 112 (DS1) to initiate an auto-slug condition. This message willhave been generated by the auto-slug mode process 328 of the hierarchyprocess wherein a start auto-slug message is transmitted to the firstupstream zone control module 116 (US1) (step 310). The event logicelement 124 evaluates whether a jam condition exists (decision node178). If it does, the auto-slug message cannot be propagated furtherupstream and corrective measures must be undertaken. Thus, continuanceof the hierarchy process (step 182) is initiated. If a jam conditiondoes not exist, the auto-slug delay timer is initiated (step 180)followed by performance of the hierarchy process (step 182). Theauto-slug delay timer allows for a certain amount of time before the“start auto-slug” message is transmitted upstream to ensure that thesystem is stable, and that a countervailing message or condition doesnot exist that would militate against an auto-slug condition. Afterperformance of the hierarchy process, the next event (event logicelement 125) in the collection of event logic elements is evaluated.

Referring now to FIGS. 9 and 13, the fourth event logic element 125evaluates a message received from the first downstream zone controlmodule 112 (DS1) to terminate an auto-slug condition. The message toterminate the auto-slug condition is first stored in memory as indicatedby the auto-slug setting 352 (step 183), and the auto-slug delay timeris cleared (step 184). The local zone control module 110 then delivers amessage to terminate the auto-slug condition to the first upstream zonecontrol module 116 (US1) (step 185) for further propagation upstream.This step is followed by evaluation of the next event (event logicelement 126) in the collection of event logic elements.

Referring now to FIGS. 9 and 14, the fifth event logic element 126 isinitiated when the auto-slug delay timer has expired, indicating that itis “safe” to enter an auto-slug condition and to propagate the “startauto-slug” message upstream. When this event occurs, the local zonecontrol module 110 stores a command to start the auto-slug function(local auto-slug register 370) (step 186), followed by performance ofthe hierarchy process (step 187). The next event (event logic element128) in the collection of event logic elements is then evaluated.

Referring to FIGS. 9 and 15, the sixth event logic element 128 isinitiated when a change in the photo-eye status of the second upstreamphoto-eye 118 (US2) is transmitted to the local zone control module 110.This event is relevant to the sleep mode process 320 of the hierarchyprocess in which the status of the second upstream photo-eye 118 (US2)is evaluated (step 254). The local zone control module 110 stores thestatus of the second upstream photo-eye 118 (US2) (step 188) in order toserve as a baseline for comparison of future photo-eye conditions,followed by performance of the hierarchy process (step 189). After theperformance of the hierarchy process, the next event (event logicelement 130) in the collection of event logic elements is evaluated.

Referring now to FIGS. 9 and 16, the seventh event logic element 130 isinitiated when a change in the photo-eye status of the first upstreamphoto-eye 116 (US1) is transmitted to the local zone control module 110.This event is relevant to the sleep mode process 320 of the hierarchyprocess in which the status of the first upstream photo-eye 116 (US1) isevaluated (step 254). The local zone control module 110 stores thestatus of the first upstream photo-eye 116 US1 (step 190) in order toserve as a baseline for comparison of future photo-eye conditions,passes this information to the first downstream zone control module 112(DS1) as photo-eye information from the second upstream zone controlmodule US2 (step 192) (thereby initiating the event logic element 128 asto the first downstream zone control module 112 (DS1)), followed byperformance of the hierarchy process (step 194). After the performanceof the hierarchy process, the next event (event logic element 132) inthe collection of event logic elements is evaluated.

Referring now to FIGS. 9 and 17, the eighth event logic element 132 isinitiated when the local zone control module 110 receives a messageconcerning a change in the photo-eye status of the first downstreamphoto-eye 112 (DS1). This event is relevant to the jam mode process 324,the auto-slug mode process 328, and the valve operation process 330,wherein the status of the first downstream photo-eye 112 (DS1) isevaluated (steps 272, 300, and 314, respectively). The local zonecontrol module 110 stores the information regarding the status of thefirst downstream photo-eye 112 (DS1) (first downstream photo-eyeregister 362) (step 196) in order to serve as a baseline for comparisonof future photo-eye conditions, transmits this information to the firstupstream zone control module 116 (US1) as information from the seconddownstream photo-eye (step 198) (thereby initiating the event logicelement 140 as to the first upstream zone control module 116 (US1)),followed by performance of the hierarchy process (step 200). After theperformance of the hierarchy process, the next event (event logicelement 134) in the collection of event logic elements is evaluated.

Referring now to FIGS. 9 and 18, the ninth event logic element 134 isinitiated when the local zone control module 110 receives a smartphoto-eye signal from the first downstream zone control module 112 (DS1)for propagation upstream to the interpreter 60. The local zone controlmodule 110 transmits this information to the first upstream zone controlmodule 116 (US1) (step 202), followed by evaluation of the next event(event logic element 136) in the collection of event logic elements.

Referring to FIGS. 9 and 19, the tenth event logic element 136 isinitiated when a release message is received from the first upstreamzone control module 116 (US1). This message will indicate whether thelocal zone control module 110 should activate its zone 13 in order torelease packages off the conveyor, or should deactivate its zone 13 inorder to prevent the transfer of packages downstream. The event logicelement first evaluates whether the local zone control module 110 is atthe downstream end of the conveyor system 10 (decision node 204). If thelocal zone control module 110 is at the downstream end of the conveyorsystem 10, its pneumatic valve is activated or deactivated (step 208)based on an input from the installation computer system 68, followed byevaluation of the next event in the collection of event logic elements.If it is not, the release message is transmitted to the first downstreamzone control module 112 (DS1) (step 206) in search of the downstream endlocal zone control module, followed by evaluation of the next event(event logic element 138) in the collection of event logic elements.

Referring now to FIGS. 9 and 20, the eleventh event logic element 138 isinitiated when the local zone control module 110 receives a slug messagefrom the first upstream zone control module 116 (US1). This message willindicate whether the local zone control module 110 should activate ordeactivate a slug condition. The event logic element first evaluateswhether the local zone control module 110 is at the downstream end ofthe conveyor system 10 (decision node 210). If it is not, the slugmessage is transmitted to the first downstream zone control module (step212), followed by evaluation of the next event (event logic element 140)in the collection of event logic elements. If the local zone controlmodule 110 is at the downstream end of the conveyor system 10, the localzone control module activates/deactivates its slug mode (step 214) basedon an input from the installation computer system 68, and transmits thisinformation to the first upstream zone control module 116 (US1) (step216) for further propagation back upstream. This is followed byevaluation of the next event (event logic element 140) in the collectionof event logic elements.

Referring now to FIGS. 9 and 21, the twelfth event logic element 140 isinitiated when the local zone control module 110 receives statusinformation from the second downstream zone control module 114 (DS2)concerning the photo-eye associated with that module. This event isrelevant to the jam mode process 324, and the auto-slug mode process328, wherein the status of the second downstream photo-eye 114 (DS2) isevaluated (steps 272 and 300, respectively).The local zone controlmodule 110 stores the information received (second downstream photo-eyeregister 364) (step 218) in order to serve as a baseline for comparisonof future photo-eye conditions, followed by performance of the hierarchyprocess (step 220). This is followed by evaluation of the next event(event logic element 142) in the collection of event logic elements.

Referring now to FIGS. 9 and 22, the thirteenth event logic element 142is initiated when the local zone control module 110 receives a slugmessage from the first downstream zone control module 112 (DS1). Thismessage will indicate whether the local zone control module 110 shouldactivate or deactivate a slug condition. The local zone control module110 first stores the received information (step 222), and then evaluateswhether a jam condition exists (decision node 224), since a slugcondition must not be inititated if a jam exists. If a jam exists, thehierarchy process is performed (step 228), followed by evaluation of thenext event (event logic element 144) in the collection of event logicelements. If a jam does not exist, the slug message is passed upstream(step 226), and the hierarchy process is performed (step 228), followedby evaluation of the next event (event logic element 144) in thecollection of event logic elements.

Referring now to FIGS. 9 and 23, the fourteenth event logic element 144is initiated when the local zone control module 110 receives an externaljam message from the first downstream zone control module 112 (DS1)indicating that a jam condition exists downstream at “x.” The local zonecontrol module 110 transmits the jam message to the first upstream zonecontrol module 116 (US1) (step 230), followed by performance of thehierarchy process (step 231), and evaluation of the next event (eventlogic element 146).

Referring now to FIGS. 9 and 24, the fifteenth event logic element 146is initiated when the sleep timer of the local zone control module 110expires, thereby activating the local zone control module 110 sleep modeand deactivating its associated zone 13. Information that the local zonecontrol module 110 is in sleep mode is stored in the local zone controlmodule 110 memory (sleeve register 366) that (step 232), followed byperformance of the hierarchy process (step 234). This is followed byevaluation of the next event (event logic element 148) in the collectionof event logic elements.

Referring now to FIGS. 9 and 25, the sixteenth event logic element 148is initiated when the local zone control module 110 jam timer hasexpired, indicating that the local zone is experiencing a jam condition.This information is stored in the local zone control module 110 memory(jam register 368) (step 236), followed by performance of the hierarchyprocess (step 238). This is followed by evaluation of the next event(event logic element 150) in the collection of event logic elements.

Referring now to FIGS. 9 and 26, the seventeenth event logic element 150is initiated when the local zone control module 110 is the lastdownstream zone control module, i.e. there are no further downstreamzone control modules, and the zone control module 110 is connecteddirectly to the installation computer 68 or a logic controller (LC) 78.In this case, the fourth pin of the 4-pin photo-eye connector is usedfor connection to and communication with the installation computer 68 orthe logic controller (LC) 70 for control of certain customer-definedmodes for handling packages at the end of the conveyor system 10. Theseventeenth event logic element 150 evaluates whether the fourth pin ofthe photo-eye connector is utilized. The event logic element firstevaluates whether this fourth pin is grounded (decision node 240). If itis, indicating that the zone control module is not the last downstreamzone control module, a slug condition is activated (step 242), followedby performance of the hierarchy process (step 246). If the fourth pin isnot grounded, indicating that the zone control module is the lastdownstream zone control module, the slug condition is deactivated (step244), followed by performance of the hierarchy process (step 246).

When the seventeenth event logic element 150 and the hierarchy processhave been completed, the collection of event logic elements returns tothe first event 120 to repeat the collection of event logic elements.

The hierarchy process is illustrated in FIGS. 27A and 27B. The hierarchyprocess is segregated into six processes: a sleep mode process 320, adownstream end module process 322, a jam mode process 324, a slug modeprocess 326, an auto-slug mode process 328, and a valve operationprocess 330.

The sleep mode process 320 first evaluates whether sleep mode is enabled(decision node 250). If sleep mode is not enabled, the downstream endmodule process 322 is performed. If sleep mode is enabled, the processthen evaluates whether the zone control module is the first upstreamzone control module at the beginning of the conveyor system 10 (decisionnode 252). If it is, the downstream end module process 322 is performed.If it is not, the process then evaluates whether the first upstreamphoto-eye, the second upstream photo-eye, and the the local photo-eyeare clear (decision node 254). If they are not, sleep mode isdeactivated (step 258), the sleep timer is deactivated (step 260), andthe downstream end module process 322 is performed. If they are, theprocess then evaluates whether sleep mode is activated (decision node256). If it is, the local zone control module valve is deactivated (step266), and the hierarchy process returns to the collection of event logicelements. If sleep mode is not activated, the process then evaluateswhether the sleep timer is running (decision node 262). If it is not,the sleep timer is reset and activated (step 264), and the downstreamend module process 322 is performed. If it is, the downstream end moduleprocess 322 is performed.

The downstream end module process 322 evaluates whether the local zonecontrol module 110 is a downstream end module, i.e. the last module inthe conveyor system 10 (decision node 268). If it is, the hierarchyprocess returns to the collection of event logic elements. If it is not,the jam mode process 324 is performed.

The jam mode process 324 first evaluates whether the jam mode is enabled(decision node 270). If it is not, the jam mode process 324 proceeds tothe slug mode process 326. If it is, the process then evaluates whetherthe local photo-eye is blocked, and the first and second downstreamphoto-eyes are clear (decision node 272). If they are, the process thenevaluates whether jam mode is activated (decision node 274). If they arenot, the process evaluates whether the local zone control module 110 hasreceived a message from the first downstream zone control module 112(DS1) to activate jam mode (decision node 275). If such a message hasnot been received, jam mode is deactivated (step 276), a message is sentto the first upstream zone control module 116 (US1) to deactivate jammode (step 278), and the jam timer is deactivated (step 280). The slugmode process 326 is then performed. If such a message has been received,the local zone control module 110 sends a message to the first upstreamzone control module 116 (US1) to deactivate slug mode, deactivateauto-slug mode, and activate jam mode (step 286). The slug mode process326 is then performed. If jam mode is activated (decision node 274), thelocal zone control module 110 sends a message to the first upstream zonecontrol module 112 (DS1) to deactivate slug mode, deactivate auto-slugmode, and activate jam mode (step 286). The slug mode process 326 isthen performed. If jam mode is deactivated, the process evaluateswhether the jam timer is running (decision node 282). If it is not, thejam timer is activated and the slug mode process 326 is performed. Ifthe jam timer is running, the slug mode process 326 is then performed.

The slug mode process 326 first evaluates whether slug mode is enabled(decision node 288). If it is not, the auto-slug mode process 328 isperformed. If slug mode is enabled, the process evaluates whether slugmode is activated for the local zone control module 110 (decision node290). If it is not, the auto-slug mode process 328 is performed. If itis, the pneumatic valve is activated (step 292), and the hierarchyprocess returns to the collection of event logic elements.

The auto-slug mode process 328 first evaluates whether the auto-slugmode is enabled (decision node 294). If it is not, valve operationprocess 330 is performed. If it is, the process then evaluates whetherthe auto-slug delay timer is activated (decision node 296). If theauto-slug delay timer is not activated, the process then evaluateswhether the first downstream zone control module 112 (DS1) photo-eye andthe second downstream zone control module 114 (DS2) photo-eye are clear(decision node 300). If they are not, the local zone control module 110transmits a message to the first upstream zone control module 116 (US1)to terminate auto-slug mode (step 306). The valve operation process 330is then performed. If the photo-eyes for the first and second downstreamzone control modules 112 (DS1), 114 (DS2) are clear, the pneumatic valvefor the local zone control module 110 is activated (step 302), the localzone control module 110 transmits a message to the first upstream zonecontrol module 116 (US1) to initiate auto-slug mode (step 310), and thehierarchy process returns to the collection of event logic elements. Ifthe auto-slug delay timer is activated (decision node 296), the processthen evaluates whether the auto-slug delay timer has expired (decisionnode 298). If it has not, the hierarchy process returns to thecollection of event logic elements. If the auto-slug delay timer hasexpired, the pneumatic valve for the local zone control module 110 isactivated (step 302), the local zone control module 110 transmits amessage to the first upstream zone control module 116 (US1) to initiateauto-slug mode (step 310), and the hierarchy process returns to theevent logic elements as shown in FIG. 9.

The valve operation process 330 first evaluates whether the photo-eyefor the first downstream zone control module 112 (DS1) is clear(decision node 314). If it is not, the pneumatic valve for the localzone control module 110 is deactivated (step 318) and the hierarchyprocess returns to the collection of event logic elements. If it is, thepneumatic valve for the local zone control module 110 is activated (step316) and the hierarchy process returns to the collection of event logicelements.

Referring again to FIG. 1, several examples of the operation of theconveyor system 10 will now be described. These include normaloperation, a jam condition, and an auto-slug condition.

Normal Operation

During normal operation, the cartons 30-34 are traveling down theconveyor (from left to right as viewed in FIG. 1). As the carton 30passes in front of the photo-eye 22, the photo-eye registers a changefrom a “clear” condition to a “blocked” condition. The zone controlmodule 20 associated with that photo-eye, considered for purposes ofthis example as the local zone control module 110, has a neighborhood ofupstream zone control modules 116 (US1), 118 (US2) and downstream zonecontrol modules 112 (DS1), 114 (DS2), as previously described. Thechange in the photo-eye condition is an event that initiates the logicprocess shown in FIG. 9. The local photo-eye event logic element, shownin FIG. 10, is triggered. Since the local photo-eye 110 is blocked bythe carton 30 (decision node 152), the delay timer is activated (step154), and the logic process continues with subsequent event logicelements and the hierarchy process. If the local photo-eye 22 becomesunblocked by the downstream movement of the carton 30 before the delaytimer expires, this again triggers the event logic element 120. Thedelay timer is then stopped (step 155) and the unblocked status of thelocal photo-eye 110 is stored. After an evaluation of whether “smartphoto-eye” is enabled, the local photo-eye unblocked status istransmitted to the first upstream zone control module 116 (US1). Thehierarchy process is then performed for the local zone control module110.

Starting with the sleep mode process 320, the hierarchy process firstevaluates at the decision node 250 whether sleep mode is enabled. If itis not, the hierarchy process proceeds to the downstream end moduleprocess 322. If sleep mode is enabled, the hierarchy process evaluateswhether the local zone control module 110 is the furthest upstream zonecontrol module (decision node 250). If it is, the hierarchy processproceeds to the downstream end module process 322, since the furthestupstream zone control module, as the first module in the conveyor system10 to receive cartons, cannot be placed in sleep mode. If the local zonecontrol module 110 is not the furthest upstream zone control module, thehierarchy process evaluates whether the first and second upstreamphoto-eyes and the local photo-eye are clear (decision node 254). If allthree photo-eyes are clear, indicating that no cartons are within thelocal and two immediately upstream zones (US1 and US2), the local zonecontrol module 110 may be placed in a sleep condition. If one of thethree photo-eyes is not clear, indicating that a carton is within thelocal or two immediately upstream zones, then the sleep condition isturned off (if the local zone control module were in the sleep conditionto begin with) (step 258) and the sleep timer is turned off (step 260),followed by performance of the downstream end module process 322. If thethree photo-eyes are clear, the hierarchy subroutine evaluates whetherthe local zone control module 110 is in a sleep condition (decision node256). If it is, the pneumatic valve is turned off, and the hierarchyprocess returns to the logic process for further evaluation of events.If the local zone control module 110 is not in a sleep condition but itis appropriate for the local zone control module 110 to be in a sleepcondition, the hierarchy process evaluates whether the sleep timer isrunning (decision node 262). If it is, the hierarchy process proceeds tothe downstream end module process 322. If it is not running, the sleeptimer is reset and turned on, and the hierarchy process proceeds to thedownstream end module process 322. In either case, when the sleep timerexpires, the event logic element 146 will be triggered, the local zonecontrol module 110 will be placed in a sleep condition (step 232), andthe sleep mode process 320 will be repeated, this time resulting in thepneumatic valve being turned off (step 266) (assuming that the twoupstream photo-eyes and the local photo-eye have not become blocked inthe meantime).

If one of the three photo-eyes is not clear (decision node 254),resulting in performance of the downstream end module process 322, thehierarchy process evaluates whether the local zone control module 110 isthe furthest downstream zone control module (decision node 268). If itis, the hierarchy process returns to the logic process for furtherevaluation of events. If it is not, the hierarchy process proceeds tothe jam mode process 324, for evaluation of whether the local photo-eye22 is blocked and if the blockage is the result of a jam condition. Ifjam mode is not enabled (decision node 270), the hierarchy processproceeds to the slug mode process 326. If jam mode is enabled, thehierarchy process evaluates whether the blockage is at the localphoto-eye and the two immediately downstream photo-eyes are clear,indicating that a jam condition is at the local zone (decision node272). If the local photo-eye is the only photo-eye that is blocked, thehierarchy process evaluates whether the status of the local zone controlmodule 110 already reflects a jam condition (decision node 274). If itdoes, the local zone control module 110 transmits a “slug off” and an“auto-slug off” message to the first upstream zone control module 116(US1) in order to prevent a slug-type conveyance of cartons downstreamtoward the jammed local zone control module 110. The local zone controlmodule 110 also transmits a “jam on” message to the first upstream zonecontrol module 116 (US1), thereby triggering the performance of theevent logic element 144 by the first upstream zone control module 116(US1). The first upstream zone control module 116 (US1) transmits the“jam on” message to its first upstream zone control module (step 230shown in FIG. 23), thereby triggering the performance of the event logicelement 144 by that zone control module, with the process being repeatedupstream. The first upstream zone control module 116 (US1) will alsoperform the hierarchy process pursuant to the event logic element 144.Since one of the downstream photo-eyes will be blocked, the hierarchysubroutine will evaluate whether a “jam on” message has been receivedfrom the first downstream zone control module 112 (DS1) (decision node275). Since a “jam on” message will have been received from the firstdownstream zone control module 112 (DS1), “slug off” and “auto-slug off”messages will be transmitted to the next upstream zone control module,and a “jam on” condition will be initiated for the subject zone controlmodule (step 286).

If, pursuant to decision node 274, the status of the local zone controlmodule 110 is not reflect a jam condition, the hierarchy processevaluates whether the jam timer is running (decision node 282) in orderto evaluate whether the blockage of the photo-eye is reflective of a jamcondition, or simply reflective of the normal carton movement down theconveyor line. If the jam timer is not running, the jam timer is turnedon (step 284), and the slug mode process 326 is performed. If the jamtimer is running, the slug mode process 326 is performed.

Pursuant to the slug mode process 326, if slug mode is not enabled(decision node 288), the hierarchy process proceeds to the auto-slugmode process 328. If slug mode is enabled, and the local zone controlmodule is in a slug condition (decision node 290), the pneumatic valveis turned on (step 292) (if it has not already been turned on), therebyensuring that cartons continue to be conveyed downstream, and thehierarchy process returns to the logic process for further evaluation ofevents. If the local zone control module is not in a slug condition, thehierarchy process proceeds to the auto-slug mode process 328.

Pursuant to the auto-slug mode process 328, the hierarchy process firstevaluates whether the auto-slug mode is enabled (decision node 294). Ifit is not, the hierarchy process proceeds to the valve operation process330. If auto-slug mode is enabled, the hierarchy process evaluateswhether an auto-slug delay timer has been started (decision node 296).If it has been started, the hierarchy process evaluates whether theauto-slug delay timer has expired (decision node 298). If it has notexpired, the hierarchy process returns to the logic process for furtherevaluation of events. If it has expired, indicating that it isappropriate for an auto slug condition to exist so that cartons can bequickly conveyed downstream, the local pneumatic valve is turned on(step 302) and the local zone control module 110 transmits a “startauto-slug” message to the first upstream zone control module 116 (US1)(step 310), thereby triggering the performance of the event logicelement 124 (FIG. 12) in the first upstream zone control module 116(US1). If the auto-slug delay timer has not been started, the hierarchyprocess evaluates whether the first and second downstream photo-eyes areclear (decision node 300), thereby indicating that the first and seconddownstream zones are available to receive cartons. If they are clear,the local pneumatic valve is turned on, and the local zone controlmodule 110 transmits a “start auto-slug” message to the first upstreamzone control module 116. If one of them is not clear, the local zonecontrol module transmits a “stop auto-slug” message to the firstupstream zone control module 116 (US1) (step 306), thereby triggeringthe event logic element 125 in the first upstream zone control module116. This is followed by performance of the valve operation process 330.

Pursuant to the valve operation process 330, the hierarchy process firstevaluates whether the first downstream photo-eye is clear (decision node314). If it is not, the local pneumatic valve is turned off (step 318),thereby preventing further conveyance of cartons downstream, and thehierarchy process returns to the logic process for further evaluation ofevents. If it is clear, the local valve is turned on (step 316), therebyenabling further conveyance of cartons downstream, and the hierarchyprocess returns to the logic process for further evaluation of events.

Jam Condition

In this example, it is assumed that the carton 30 of FIG. 1 has becomejammed and unable to move further downstream. With respect to thisexample, the local zone control module 110 (L) in FIG. 8 is the zonecontrol module associated with the jammed carton. It is also assumedthat the system configuration has a sleep timer interval of fiveseconds, sleep mode and jam mode are enabled, but auto-slug mode is notenabled. Since the local photo-eye remains blocked by the jammed carton30 (decision node 152), the photo-eye delay timer is started (step 154),and will eventually expire, thereby triggering event logic element 122.The local photo-eye status is stored (step 166) and, assuming that thelocal photo-eye has not been designated a smart photo-eye, the firstupstream zone control module 116 (US1) receives a message from the localzone control module 110 which it interprets as a message from a firstdownstream zone control module concerning the local photo-eye status(step 172). The hierarchy process is then performed, beginning with thesleep mode process 320. Since sleep mode is enabled (decision node 250),the process proceeds to decision node 252 for evaluation of whether thelocal zone control module 110 is the first upstream zone control module.Assuming that it is not, the process evaluates whether the two upstreamand local photo-eyes are clear (decision node 254). Since the localphoto-eye is not clear due to the jam condition, the sleep condition isturned off (step 258) and the sleep timer is turned off (step 260). Thedownstream end module process 322 is then evaluated (decision node 268).Assuming that the local zone control module 110 is not the furthestdownstream zone control module, the jam mode process 324 is performed.Since jam mode is enabled (decision node 270), the process evaluateswhether the local photo-eye is blocked (which it is, because of the jamcondition) and whether the first two downstream photo-eyes are clear(decision node 272). If the two downstream photo-eyes are clear, theprocess evaluates whether a jam condition exists at the local zonecontrol module 110 (decision node 274). Since it does, the local zonecontrol module 110 transmits “slug off” and “auto-slug off” messages tothe first upstream zone control module 116 (US1), and transmits a “jamon” message to the first upstream zone control module 116 (US1), therebytriggering the event logic element 144 to the first upstream zonecontrol module 116 (US1). The “jam on” message will be propagatedupstream pursuant to the event logic element 144. At some upstream zonecontrol module, the local and first two downstream photo-eyes will beclear since the jam condition will exist further downstream (decisionnode 272). Since a “jam on” message will have been received from thefirst downstream zone control module 112 (DS1) (decision node 275), thezone control module will transmit “slug off” and “auto-slug off”messages to the next upstream zone control module, and will transmit a“jam on” message to the next upstream zone control module, therebytriggering the event logic element 144 to the next upstream zone controlmodule.

Auto-Slug Condition

With respect to this example, it is assumed that the systemconfiguration has a sleep timer interval of five seconds, and that sleepmode, jam mode, and auto-slug mode are enabled, and the slug mode isdisabled. Referring to FIG. 1, it is also assumed that the local zonecontrol module 110 is associated with one of the optical sensors 22between the cartons 30, 32 and, thus, is clear, that the second upstreamphoto-eye is blocked by the carton 32, and that the local zone controlmodule 110 has received a message from the first downstream zone controlmodule 112 (DS1) to activate the auto-slug feature (event 124). Sincethe jam mode is not activated (decision node 178), the auto-slug delaytimer for the local zone control module 110 is activated (step 180), andthe hierarchy process is initiated.

Since, pursuant to the above assumptions, sleep mode is enabled(decision node 250), the local zone control module 110 is not anupstream end zone control module (decision node 252), and the secondupstream photo-eye is not clear (decision node 254), the sleep conditionis turned off (step 258) and the sleep timer is turned off (step 260),and the downstream end module process 322 is performed.

Pursuant to the above assumptions, the local zone control module 110 isnot a downstream end zone control module (decision node 268), and jammode is enabled (decision node 270). Since the local photo-eye is notblocked, the conditions of decision node 272 are not satisfied. Thelocal zone control module 110 has not received a “jam on” message fromthe first downstream zone control module 112 (DS1) (decision node 275),so the local zone control module 110 sets the jam condition to “off”(step 276), indicating the absence of a jam condition, sends a “jam off”message to the first upstream zone control module 116 (US1) (step 278),and turns the jam timer off (step 280). The slug mode process 326 isthen performed.

Slug mode is not enabled (decision node 288) pursuant to the aboveassumptions, but auto-slug mode is enabled (decision node 294). Theauto-slug mode process 328 first evaluates whether the auto-slug delaytimer has been started (decision node 296). If the auto-slug delay timerhas not been started, and the first and second downstream photo-eyes areclear (decision node 300), or if the auto-slug delay timer has beenstarted (decision node 296) and has expired (decision node 298), thepneumatic valve is activated (step 302) and the local zone controlmodule 110 transmits a message to the first upstream zone control module116 (US1) to initiate an auto-slug condition (step 310), therebytriggering event logic element 124 in the first upstream zone controlmodule 116 (US1). This process is propagated upstream so that thecartons 32, 34 are quickly transferred along the conveyor system 10. Ifthe auto-slug delay timer has not expired (decision node 298), thehierarchy process returns to the logic process for further evaluation ofevents. If the auto-slug delay timer has not been started, and one ofthe first and second downstream photo-eyes are not clear (decision node300), the local zone control module 110 transmits a message to the firstupstream zone control module 116 (US1) to stop the auto-slug condition(step 306). The valve operation process 330 is then performed.

Pursuant to the valve operation process 330, if the first downstreamphoto-eye is clear (decision node 314), the local pneumatic valve isturned on (step 316) to convey cartons downstream. If the firstdownstream photo-eye is not clear, the local pneumatic valve is turnedoff (step 318), to prevent further conveyance of cartons through thelocal zone. In either case, the hierarchy process returns to the logicprocess for continued performance of event logic elements.

The conveyor system 10 described herein provides a high degree ofcontrol and flexibility. The collection of event logic elements andhierarchy process described herein provide a superior means ofcontrolling and monitoring the performance of the conveyor system andproviding appropriate responses to different performance conditions,such as package jams or excessive capacity. The ability to selectdifferent mode of operation, such as jam mode or auto-slug mode, and toplace selected zones of the conveyor system 10 in sleep mode, provide adegree of flexibility precisely tailored to the conditions associatedwith a specific run of packages. Energy savings can be realized byemploying sleep mode, and, because the location of a jam condition canbe precisely identified and its location propagated to the installationcomputer system 68 through the interpreter 60, package jams can bequickly corrected, thereby saving operator time and resources. Becausezone control modules are identified by position in the conveyor system10 rather than by a unique identification number, a zone control modulecan be quickly replaced without the necessity of reprogramming acomputer with a new module identification number. Similarly, theconveyor system 10 can be readily expanded with additional zone controlmodules without the necessity of reprogramming the new moduleidentification numbers.

The zone control modules, interpreter, PDA, server and all othercomponents can be operably interconnected to one another in a mannerwhich would be apparent to one skilled in the art and the exemplaryembodiments of such operable interconnection described herein shall notbe construed as limiting on the invention since anycommunications-enabled interconnection between zone control modules andthe other components referred to above can be employed, such as typicalwire-based connections (Ethernet, coaxial, connecter-based conduit,etc.) or wireless communications in any of the accepted networkprotocols, without departing from the scope of this invention.

The collection of event logic events 120-150 and the processes 320-330comprising the hierarchy process have been arranged in exemplarysequences in the preferred embodiment described herein. However, theevent logic events 120-150 and the processes 320-330 may be arranged inother sequences which would be apparent to one skilled in the artwithout departing from the scope of the invention, and the exemplarysequences described herein shall not be construed as limiting on theinvention.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation. Reasonable variationand modification are possible within the scope of the foregoingdisclosure and drawings without departing from the scope of theinvention.

1. A method for controlling a conveyor system separated into a pluralityof contiguous independently-controllable zones comprising the steps of:providing a plurality of actuators, each actuator operablyinterconnected to a particular one of the plurality ofindependently-controllable zones, wherein each actuator operates themovement of at least one object in the particular zone; providing aplurality of controllers having a signal processor/generator therein;operably interconnecting each controller with a particular one of theplurality of actuators for selective actuation of the particularactuator and operably interconnecting the controller with at least oneof an adjacent upstream controller and an adjacent downstreamcontroller; and having each controller perform at least one of thefollowing steps: detecting the presence of at least one object local tothe controller and performing at least one event logic elementresponsive to the detecting step; receiving a signal from at least oneof the adjacent upstream controller and the adjacent downstreamcontroller and performing at least one event logic element responsive tothe signal; detecting a change in an operating condition stored by thecontroller and performing at least one event logic element responsive tothe changed operating condition.
 2. The method of claim 1 and furthercomprising the step of initiating the operation of a delay timer inresponse to the presence of an object in a zone local to the controller.3. The method of claim 1 and further comprising the step of terminatingthe operation of the delay timer in response to the absence of an objectin a zone local to the controller for a predetermined period of time. 4.The method of claim 2 and further comprising the step of communicatingthe absence of the object to at least one adjacent upstream controller.5. The method of claim 1 and further comprising the step of storing theresults of the detecting step in the controller to serve as a referencefor further evaluation of the presence of an object in the zone.
 6. Themethod of claim 5 and further comprising the step of communicating theresults of the detecting step to at least one adjacent upstreamcontroller.
 7. The method of claim 1 and further comprising the step ofresponding to a signal representative of an auto-slug condition receivedfrom at least one adjacent downstream controller.
 8. The method of claim7 and further comprising the step of determining whether a jammed objectcondition exists in a zone local to the controller.
 9. The method ofclaim 7 and further comprising the step of storing the received signalrelating to the jammed object condition to serve as a reference forevaluation of a subsequent received signal representative of a jammedobject condition.
 10. The method of claim 9 and further comprising thestep of initiating the operation of a delay timer in response todetected jammed object condition.
 11. The method of claim 10 and furthercomprising the step of terminating the operation of the delay timer whenthe jammed object condition fails to be detected for an acceptableperiod of time.
 12. The method of claim 11 and further comprising thestep of communicating the signal to at least one adjacent upstreamcontroller representative of the jammed object condition.
 13. The methodof claim 1 and further comprising the step of responding to a change inthe operation of a timer.
 14. The method of claim 13 and furthercomprising the step of storing an auto-slug setting representative ofwhether at least one of the plurality of controllers is initiating anauto-slug condition.
 15. The method of claim 13 and further comprisingthe step of storing a sleep setting representative of the initiation ofa sleep condition to serve as a reference for further evaluation of asleep condition.
 16. The method of claim 13 and further comprising thestep of storing a jam setting representative of a jam condition to serveas a reference for further evaluation of a jam condition.
 17. The methodof claim 1 and further comprising the step of responding to a signalreceived that is representative of the presence of an object from anupstream zone.
 18. The method of claim 17 and further comprising thestep of storing the signal relating to the presence of an object localto an upstream controller to serve as a reference for further evaluationof the presence of an object local to an upstream controller.
 19. Themethod of claim 18 and further comprising the step of communicating asignal to at least one adjacent downstream controller representative ofstate of the upstream controller.
 20. The method of claim 1 and furthercomprising the step of responding to a signal representative of thepresence of an object local to a downstream controller.
 21. The methodof claim 20 and further comprising the step of storing the signalrelating to the presence of an object local to a downstream controllerto serve as a reference for evaluation of a subsequent received signalrelative to the presence of an object local to a downstream controller.22. The method of claim 21 and further comprising the step ofcommunicating the signal to at least one adjacent upstream controllerrepresentative of the state of the downstream controller.
 23. The methodof claim 1 and further comprising the step of responding to a signalfrom an adjacent downstream controller relating to the status of anobject detector as a smart object detector.
 24. The method of claim 23and further comprising the step of communicating a signal to at leastone adjacent upstream controller representative of the state of thedownstream controller as having a smart object detector.
 25. The methodof claim 1 and further comprising the step of responding to a signalfrom an adjacent upstream controller concerning the release of an objectfrom an upstream zone.
 26. The method of claim 25 and further comprisingthe step of determining whether the controller is adjacent to adownstream controller.
 27. The method of claim 26 and further comprisingthe step of communicating the signal to at least one adjacent downstreamcontroller representative of the result of the evaluating step.
 28. Themethod of claim 26 and further comprising the step of operating theactuator corresponding to the controller local to the zone in responseto the received signal in order to actuate the actuator and operate themovement of objects in the zone local to the controller.
 29. The methodof claim 1 and further comprising the step of responding to a signalreceived that is representative of a change in a slug condition from atleast one upstream controller.
 30. The method of claim 29 and furthercomprising the step of determining whether the controller is adjacent adownstream controller.
 31. The method of claim 30 and further comprisingthe step of communicating the signal to at least one adjacent downstreamcontroller representative of the slug condition in the at least oneadjacent downstream controller.
 32. The method of claim 30 and furthercomprising the step of updating the slug condition in the localcontroller in response to the received signal.
 33. The method of claim32 and further comprising the step of communicating the slug conditionto at least one adjacent upstream controller to update a slug conditionin the at least one adjacent upstream controller.
 34. The method ofclaim 1 and further comprising the step of responding to a signal froman adjacent downstream controller relating to presence of an objectlocal to the zone of the adjacent downstream controller.
 35. The methodof claim 34 and further comprising the step of storing the signal fromthe adjacent downstream controller representative of the presence of theobject local to the zone of the adjacent downstream controller.
 36. Themethod of claim 1 and further comprising the step of responding to asignal received from at least one downstream controller representativeof a change in a slug condition.
 37. The method of claim 36 and furthercomprising the step of storing the signal from the at least onedownstream controller representative of the change in the slug conditionto serve as a reference for evaluation of a subsequent received signalrepresentative of a change in a slug condition.
 38. The method of claim37 and further comprising the step of determining whether a jamcondition exists.
 39. The method of claim 38 and further comprising thestep of communicating a signal representative of the slug condition toat least one upstream controller to propagate the slug condition to theat least one upstream controller if the jam condition is determined notto exist.
 40. The method of claim 1 and further comprising the step ofresponding to a signal received from at least one downstream controllerrepresentative of a jam condition.
 41. The method of claim 40 andfurther comprising the step of communicating the signal representativeof the jam condition to at least one upstream controller to propagatethe jam condition to the at least one upstream controller.
 42. Themethod of claim 1 and further comprising the step of responding to theexpiration of a sleep timer.
 43. The method of claim 42 and furthercomprising the step of storing information representative of theinitiation of a sleep condition to serve as a reference for furtherevaluation of the sleep condition of the controller.
 44. The method ofclaim 1 and further comprising the step of responding to the expirationof a jam timer.
 45. The method of claim 44 and further comprising thestep of storing information representative of the activation of a jamcondition to serve as a reference for further evaluation of the jamcondition of the controller.
 46. The method of claim 1 and furthercomprising the step of determining whether the operable interconnectionsof the controller to at least one of the upstream controller and thedownstream controller is in a ground state.
 47. The method of claim 46and further comprising the step of initiating a slug condition in thecontroller if the detecting step detects a ground state.
 48. The methodof claim 46 and further comprising the step of terminating a slugcondition in the controller if the detecting step does not detect aground state.
 49. The method of claim 1 and further comprising the stepof responding to a determination of whether a sleep mode is enabled. 50.The method of claim 49 and further comprising the step of determiningwhether the controller is a downstream end controller if sleep mode isnot enabled.
 51. The method of claim 49 and further comprising the stepof determining whether the controller is an upstream end controller ifsleep mode is enabled.
 52. The method of claim 51 and further comprisingthe step of determining whether the controller and at least one upstreamcontroller have detected the presence of an object.
 53. The method ofclaim 52 and further comprising the step of initiating a sleep conditionand deactivating a sleep timer if at least one of the controller and atleast one adjacent upstream controller detect the presence of an objectin a zone local to the at least one of the controller and the at leastone adjacent upstream controller.
 54. The method of claim 52 and furthercomprising the step of determining whether a sleep condition is activeif the controller and at least one adjacent upstream controller do notdetect the presence of an object in a zone local to the controller andat least one adjacent upstream controller.
 55. The method of claim 54and further comprising the step of determining whether a sleep timer isrunning if the sleep condition is not active.
 56. The method of claim 55and further comprising the step of at least one of resetting andactivating the sleep timer if the sleep timer is not running.
 57. Themethod of claim 56 and further comprising the step of determiningwhether the controller is a downstream end controller if the sleep timeris running.
 58. The method of claim 54 and further comprising the stepof deactivating the actuator corresponding to the controller local tothe zone if a sleep condition is active.
 59. The method of claim 1 andfurther comprising the step of responding to a determination of whetherthe controller is a downstream end controller.
 60. The method of claim59 and further comprising the step of determining whether a jam mode isenabled if the controller is not a downstream end controller.
 61. Themethod of claim 1 and further comprising the step of responding to adetermination of whether a jam mode is enabled.
 62. The method of claim61 and further comprising the step of determining whether an object ispresent in a zone local to the controller and an object is not presentin either a first downstream zone or a second downstream zone.
 63. Themethod of claim 62 and further comprising the step of determiningwhether a signal representative of a jam condition in the firstdownstream controller has been received by the controller if an objectpresent in a zone local to the controller and an object is present inboth the first downstream zone and the second downstream zone.
 64. Themethod of claim 63 and further comprising the step of deactivating thejam condition, sending a signal representative of the jam condition tothe first upstream controller, and deactivating the jam timer, if asignal representative of an active jam condition has not been receivedfrom the first downstream controller.
 65. The method of claim 63 andfurther comprising the step of sending a signal representative of aterminated slug condition, deactivating an auto-slug condition, andsending a signal representative of an activated jam condition to thefirst upstream controller if a signal representative of an activated jamcondition has been received from the first downstream controller. 66.The method of claim 62 and further comprising the step of determiningwhether a jam condition exists if an object is present in the zone localto the controller and an object is not present in at least one of thefirst downstream zone and the second downstream zone.
 67. The method ofclaim 66 and further comprising the step of determining whether a jamtimer is running if a jam condition does not exist.
 68. The method ofclaim 67 and further comprising the step of activating the jam timer ifthe jam timer is not running.
 69. The method of claim 67 and furthercomprising the step of determining whether a slug mode is enabled if thejam timer is running.
 70. The method of claim 66 and further comprisingthe step of sending a signal representative of a deactivated slugcondition and a deactivated auto-slug condition local to the controller,and sending a signal representative of an activated jam condition to thefirst upstream controller if a jam condition is detected.
 71. The methodof claim 1 and further comprising the step of responding to adetermination of whether a slug mode is enabled.
 72. The method of claim71 and further comprising the step of determining whether a current slugcondition exists if slug mode is enabled.
 73. The method of claim 71 andfurther comprising the step of determining whether auto-slug mode isenabled if slug mode is not enabled.
 74. The method of claim 72 andfurther comprising the step of determining whether auto-slug mode isenabled if the current slug condition does not exist.
 75. The method ofclaim 72 and further comprising the step of activating the actuatorcorresponding to the controller local to the zone if the slug conditiondoes exist.
 76. The method of claim 1 and further comprising the step ofresponding to a determination of whether auto-slug mode is enabled. 77.The method of claim 76 and further comprising the step of determiningwhether a first downstream object detector does not detect an object ifauto-slug mode is not enabled.
 78. The method of claim 76 and furthercomprising the step of determining whether an auto-slug delay timer hasbeen started if auto-slug mode is enabled.
 79. The method of claim 78and further comprising the step of determining whether a firstdownstream object detector and a second downstream object detector eachdo not detect an object if the auto-slug delay timer is not running. 80.The method of claim 79 and further comprising the step of sending asignal to a first upstream controller representative of a stop auto-slugcondition if the first downstream object detector or the seconddownstream object detector each do not detect the object.
 81. The methodof claim 79 and further comprising the step of activating the actuatorcorresponding to the controller local to the zone if the firstdownstream object detector and the second downstream object detectoreach do not detect an object.
 82. The method of claim 78 and furthercomprising the step of determining whether the auto-slug delay timer hasexpired if the auto-slug delay timer has been started.
 83. The method ofclaim 82 and further comprising the step of activating the actuatorcorresponding to the controller local to the zone if the auto-slug delaytimer has expired.
 84. The method of claim 83 and further comprising thestep of sending a signal to a first upstream controller representativeof a start auto-slug condition.
 85. The method of claim 84 and furthercomprising the step of sending a signal to a first upstream controllerrepresentative of a start auto-slug condition.
 86. The method of claim 1and further comprising the step of responding to a determination of achange in state of a first downstream object detector.
 87. The method ofclaim 86 and further comprising the step of activating the actuatorcorresponding to the controller local to the zone if the firstdownstream photo-eye is clear.
 88. The method of claim 86 and furthercomprising the step of deactivating the actuator corresponding to thecontroller local to the zone if the first downstream object detectordoes detect an object.
 89. The method of claim 14 and further comprisingthe step of activating the particular one of the plurality of actuatorsin response to a signal initiated by the at least one event logicelement.
 90. The method of claim 14 and further comprising the step ofperforming a plurality of event logic elements for evaluating andcontrolling the position of the at least one object in the plurality ofzones, and transmitting a signal relating to the position of the atleast one object to the at least one of the adjacent upstream controllerand the adjacent downstream controller.
 91. The method of claim 90 andfurther comprising the step of determining whether to actuate aparticular one of the actuators responsive to a hierarchy process calledby an event logic element based on the enablement of at least onefunction mode.
 92. The method of claim 91 wherein the at least onefunction mode comprises at least one of a sleep mode, a downstream endmodule mode, a jam mode, a slug mode, an auto-slug mode, and a valveoperation mode.